Embodiments in accordance with the present invention relate to a manufacturing method of a thin film magnetic head utilized for reading/writing to a magnetic disk system.
The needs for storing images and music, etc. in a hard-disk drive have been spreading rapidly to such an extent that they are seen as hard-disk drives added to video recorders and hard-disk drives built into televisions, etc. With the increase in image data, there is a demand for increased density, even in the longitudinal recording density of a magnetic disk drive. Currently, in order to achieve a high recording density of 100 Gbit/inch2 or more in a magnetic head, the transfer in technology from a longitudinal recording to a perpendicular recording has been progressing rapidly. This is due to thermal fluctuations of the magnetization which occur in the medium when the bit length is made smaller, and the longitudinal recording density cannot be increased in the case when a current longitudinal recording method is used.
On the other hand, in a perpendicular magnetic recording method, this thermal fluctuation can be avoided because it is magnetized in the perpendicular direction of the medium. Moreover, since a single pole head is used for recording, the magnetic loss is small, and since there is a soft under layer on the medium side, the recording ability is also improved. This also becomes a motivation for the aforementioned transfer to a perpendicular magnetic head. By the way, in this perpendicular write head, an improvement in the longitudinal recording density is required. In order to achieve this, it is necessary to reduce the write track width. However, the reduction of the recording track brings a decrease in the magnetic field applied to the magnetic recording disk from the tip of the main pole. In order to prevent this decrease in the magnetic field, a thicker film thickness of the main pole is preferable. On the other hand, in a magnetic disk system, it is necessary to read/write over a wide range from the inner radius to the outer radius of the magnetic recording disk. At this time, the read/write is performed in a state where the magnetic head has a skew angle of about 0 to 15° against the tangent in the rotation direction of the magnetic recording disk at the inner radius and the outer radius of the magnetic recording disk. In this case, a problem arises where the adjacent track is erased when the shape of the main pole at the air bearing surface is rectangular, so that the write track width cannot be reduced. To solve the problem, a so-called reverse-trapezoid shaped main pole is proposed, which will accommodate the narrow track width, that is, by the track width at the reading side of the main pole being made narrower than the width at the trailing side of the main pole. As a manufacturing method of a magnetic head having a reverse-trapezoid shaped main pole, a manufacturing method, especially applying an ion milling technique, is disclosed. For instance, JP-A No. 18836/2005 A discloses a manufacturing method applying an ion milling technique by using a resist, a non-magnetic insulation film, and a non-magnetic metal film as a mask. Moreover, JP-A No. 203311/2003 A discloses an ion milling angle for processing a reverse-trapezoid shape by using a buffer layer as a mask.
However, when a manufacturing method using an ion milling technique is applied to the aforementioned formation process of a main pole, a magnetic material which is a main pole material etched by ion milling, and alumina and an organic resin which are mask materials inevitably adhere again to the side face of the mask of the main pole in the track direction. The re-deposition film formed like this remains like a fence after removing the resist. If the re-deposition film remains, it brings such problems like the creation of a starting-point of voids during formation of alumina in the following process, and coverage failure, and, as another problem, a non-uniform plating failure occurs which is due to the failure of the under-layer while forming a shield for an improvement of the field gradient by plating. Thus, the yield not only is remarkably decreased, but it also causes a characteristic deterioration, and the reliability will be reduced when the re-deposition film remains.